JP2018039259A - Laminate film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate film having a resin layer that has versatile adhesiveness on a solvent-free coating such as a prism resin, and also resists decreasing in adhesiveness due to UV irradiation in a working process to maintain excellent adhesiveness.SOLUTION: A laminate film has a resin layer (X) on at least one face of a polyester film. For the resin layer (X), a change of surface energy (the sum of polar power and hydrogen bond power and dispersion power) is 0.1 mN/m or more and 15 mN/m or less before and after UV irradiation treatment.SELECTED DRAWING: None

Description

  The present invention relates to a laminated film in which a resin layer is laminated on at least one surface of a polyester film.

Thermoplastic resin films, especially polyester films, are used for magnetic recording materials, packaging materials, flat displays, etc. because they have excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency, and chemical resistance. Widely used for optical films such as antireflection films, diffusion sheets, prism sheets, and transparent touch panels.
However, in these applications, when other materials are applied and laminated on the polyester film, there is a disadvantage that the adhesiveness is poor depending on the materials used.

Therefore, as one method for imparting adhesiveness to the surface of the polyester film, a method is known in which various resins are applied to the surface of the polyester film to provide an application layer having easy adhesion performance. In particular, a technique for improving the adhesiveness by providing a coating layer made of a polyurethane resin is known.

  In order to solve the above-mentioned problems, a method of laminating a polyurethane resin layer having a low glass transition point on a polyester film and imparting adhesiveness to an overcoat layer (Patent Document 1), or a specific functional group on an unstretched film A method of laminating a resin layer having adhesion to the vapor-deposited layer by applying and stretching urethane resin (Patent Document 2), wide saponification by making the resin layer made of alicyclic urethane into a specific surface energy A method for imparting adhesiveness to PVA having a degree (Patent Document 3), a method for imparting adhesiveness to a hard coat by similarly controlling the surface energy and functional group index of the resin layer (Patent Document 4), etc. Has been proposed.

Japanese Patent No. 5263320 JP 2010-131885 A JP2013-240993A JP 2014-188937 A

  However, in Patent Document 1, since a resin layer having a low glass transition point is laminated on the surface of the polyester film, when the resin layer reaches a temperature higher than the glass transition point, the resin layer changes. It may not be applicable for use. Moreover, when a polyester film is stored in a roll state, the polyester films may block each other and may not be suitable for practical use. Further, as in Patent Document 2, the method of laminating a resin layer using a urethane resin having a specific functional group on a polyester film can improve a certain adhesiveness by urethane bonding, but is particularly a prism resin. Adhesiveness is not sufficient with respect to the solventless topcoat layer. In addition, as in Patent Document 3, in a method of imparting adhesiveness with PVA having a wide saponification degree by making a resin layer made of alicyclic urethane a specific surface energy, a hard coat resin, a prism resin, etc. In general, there is a problem in general-purpose adhesiveness such as deterioration of adhesiveness with a resin having a hydrophobic acrylic skeleton. Patent Document 4 also has a problem in general-purpose adhesion as in Patent Document 3 in the method of imparting adhesiveness to a hard coat by controlling the surface energy and functional group index of the resin layer.

  Furthermore, in Patent Documents 1 to 4, when a UV curable resin such as a hard coat resin or a prism resin is processed many times in the same process, the resin layer deteriorates due to UV irradiation, and the overcoat layer peels off accordingly. There is a danger that it will end up.

  Therefore, in the present invention, the above-mentioned drawbacks are solved, and particularly for non-solvent paints such as prism resins, it has general-purpose adhesiveness, and further suppresses a decrease in adhesiveness due to UV irradiation in the processing step, thereby achieving good adhesion. It aims at providing the laminated film which has a resin layer which maintains property.

The present invention has the following configuration. That is,
[I] A laminated film having a resin layer (X) on at least one surface of a polyester film, wherein the resin layer (X) has surface energy (polarity and hydrogen bonding strength before and after UV irradiation treatment under the following conditions): The change in the sum of dispersion forces (surface energy after UV irradiation treatment-surface energy before UV irradiation treatment) is 0.1 mN / m or more and 15 mN / m or less.

[UV irradiation conditions]
UV irradiation device: Condensing type high-pressure mercury lamp (H03-L31, manufactured by Eye Graphics Co., Ltd.)
Irradiation intensity: 120 W / cm
Irradiation distance (distance between UV irradiation device and irradiated object): 12cm
Integrated irradiation intensity: 500 mJ / cm ² or more and 1000 mJ / cm ² or less.
[II] The resin layer (X) has a change in the sum of the polar force and the hydrogen bonding force before and after the UV irradiation treatment under the above conditions (the sum of the polar force and the hydrogen bonding force after the UV irradiation treatment-before the UV irradiation treatment) The laminated film according to [I], wherein the sum of the polar force and the hydrogen bonding force is 10 mN / m or less.
[III] The laminated film according to [I] or [II], in which the resin layer (X) has a urethane bond and / or an acryloyl group.
[IV] Any one of [I] to [III], wherein a minimum reflectance in a wavelength range of 400 nm to 700 nm measured from the resin layer (X) side is 5.0% to 6.5%. Laminated film.
[V] The laminated film according to any one of [I] to [IV], in which the resin layer (X) has a polycyclic aromatic hydrocarbon structure.
[VI] The laminated film according to any one of [I] to [V], which is used for easy adhesion for a prism sheet.
[VII] A method for producing a laminated film having a resin layer (X) on at least one surface of a polyester film and satisfying the following (1) and (2):
The manufacturing method of a laminated | multilayer film including the process of apply | coating the resin composition containing an isocyanate compound (A) to at least one surface of a polyester film, and forming the resin layer (X) which consists of resin ((alpha)) obtained by heating.
(1) Change in surface energy (sum of polar force, hydrogen bonding force and dispersion force) before and after UV irradiation treatment under the following conditions (surface energy after UV irradiation treatment-before UV irradiation treatment) Surface energy) of 0.1 mN / m or more and 15 mN / m or less.
(2) The resin layer (X) has a change in the sum of the polar force and the hydrogen bonding force before and after the UV irradiation treatment under the following conditions (the sum of the polar force and the hydrogen bonding force after the UV irradiation treatment-before the UV irradiation treatment). The sum of the polar force and the hydrogen bond strength) is less than 10 mN / m.

[UV irradiation conditions]
UV irradiation device: Condensing type high-pressure mercury lamp (H03-L31, manufactured by Eye Graphics Co., Ltd.)
Irradiation intensity: 120 W / cm
Irradiation distance (distance between UV irradiation device and irradiated object): 12cm
Integrated irradiation intensity: 500 mJ / cm ² or more and 1000 mJ / cm ² or less.
[VIII] The method for producing a laminated film according to [VII], wherein the isocyanate compound (A) is a branched blocked isocyanate.
[IX] The method for producing a laminated film according to [VII] or [VIII], wherein the content of the isocyanate compound (A) in the resin composition is 50 to 95% by mass.
[X] The method for producing a laminated film according to any one of [VII] to [IX], wherein the resin composition contains at least one compound (B) selected from a melamine compound, an oxazoline compound, and a carbodiimide compound.

  According to the present invention, the resin layer laminated on the polyester film has general-purpose adhesiveness particularly for solvent-free paints such as prism resin, and further suppresses the deterioration of adhesiveness due to UV irradiation in the processing process. And the laminated | multilayer film which show | plays the effect of maintaining favorable adhesiveness can be provided.

  Hereinafter, the laminated film of the present invention will be described in detail.

The present invention is a laminated film having a resin layer (X) on at least one surface of a polyester film. The laminated film of the present invention exhibits good general-purpose adhesiveness with respect to solventless paints such as prism resins.
(1) Resin layer (X)
The laminated film of the present invention has a resin layer (X) on at least one surface of a polyester film, and changes in surface energy (the sum of polar force, hydrogen bonding force, and dispersion force) before and after UV irradiation treatment under the following conditions. (Surface energy after UV irradiation treatment−surface energy before UV irradiation treatment) is required to be 0.1 mN / m or more and 15 mN / m or less.

[UV irradiation conditions]
UV irradiation device: Condensing type high-pressure mercury lamp (H03-L31, manufactured by Eye Graphics Co., Ltd.)
Irradiation intensity: 120 W / cm
Irradiation distance (distance between UV irradiation device and irradiated object): 12cm
Integrated irradiation intensity: 500 mJ / cm ² or more and 1000 mJ / cm ² or less.
By reducing the surface energy (the sum of polar force, hydrogen bonding force, and dispersion force) before and after UV irradiation treatment to 15 mN / m or less, the deterioration of adhesiveness due to UV irradiation in the processing process is suppressed and good. High adhesiveness can be maintained. The change in surface energy (the sum of polar force, hydrogen bonding force, and dispersion force) before and after UV irradiation treatment is preferably small, but the resin layer (X) composed of organic matter is inevitably deteriorated by UV irradiation. , It is practically difficult to make it less than 0.1 mN. More preferably, it is 0.1 N / m or more and 10.0 N / m or less.

  In the laminated film of the present invention, the resin layer (X) has a change in the sum of the polar force and the hydrogen bonding force before and after the UV irradiation treatment under the above conditions (the sum of the polar force and the hydrogen bonding force after the UV irradiation treatment). -The sum of the polar force and the hydrogen bonding force before the UV irradiation treatment is preferably 10 mN / m or less. In the resin layer (X), the change in the sum of the polar force and the hydrogen bonding force before and after the UV irradiation treatment is 10 mN / m or less, so that not only the initial adhesiveness but also the adhesion by UV irradiation in the subsequent processing steps. Deterioration can be suppressed, and good adhesiveness can be maintained. From the viewpoint of maintaining adhesiveness in a humid heat environment, it is more preferably 0.1 N / m or more and 7.0 N / m or less.

  In the present invention, the dispersion force is one of the forces constituting the surface energy of the resin layer (X), and is an index representing the degree of intermolecular force generated by the main chain such as a hydrocarbon chain, and is hydrophobic. The size of the interaction is shown. The polar force is one of forces constituting the surface energy of the resin layer (X) and is an index representing the degree of intermolecular force generated by the polar group in the molecule. The hydrogen bonding force is an index representing the degree of intermolecular force due to the electronegativity of the resin layer (X). Since the polar force and the hydrogen bonding force are generated by a polar group having hydrogen such as a hydroxyl group, a carboxyl group, or an amino group, the magnitude of the hydrophilic and hydrophobic interaction with respect to the dispersion force is indicated.

  In the present invention, by controlling the dispersion force, polarity force, sum of hydrogen bonding force, and each component of the resin layer (X) within a specific range, not only initial adhesiveness but also UV in the subsequent processing steps. A decrease in adhesiveness due to irradiation can be suppressed and good adhesiveness can be maintained.

  It is preferable that resin layer (X) of this invention contains resin ((alpha)) obtained by apply | coating the resin composition containing an isocyanate compound (A), and heating. Moreover, at least 1 or more types of compounds (B) chosen from a melamine compound, an oxazoline compound, and a carbodiimide compound may be included.

  In the laminated film of the present invention, the resin layer (X) preferably contains a urethane bond and / or an acryloyl group. Since the resin layer (X) contains a urethane bond and / or an acryloyl group, it is possible to control the surface energy of the resin layer (X), and it adheres well to UV-curable solventless paints such as prism resins. Sex can be easily expressed. In addition, although it is preferable that a urethane bond and / or an acryloyl group are contained in resin ((alpha)) mentioned later, it is not this limitation.

  The laminated film of the present invention preferably has a minimum reflectance of 5.0% or more and 6.5% or less in a wavelength range of 400 nm or more and 700 nm or less as measured from the resin layer (X) side. For the laminated film, if the minimum reflectance in the range of 400 nm or more and 700 nm or less of the surface on which the resin layer (X) is laminated is 5.0% or more, the laminated film is applied to the prism sheet substrate, When used as a sheet, not only general-purpose adhesiveness can be obtained with respect to a solventless paint such as a prism resin, but also an effect of improving luminance can be obtained. The minimum reflectance of 6.5% or less is a substantial upper limit of the resin material when using the polyester film as a base material. Regarding the laminated film, the method of setting the minimum reflectance in the range of 400 nm or more and 700 nm or less on the surface on which the resin layer (X) is laminated is not particularly limited, but the refraction of the resin layer (X) is not limited. When the rate is increased or the thickness of the resin layer (X) is reduced (for example, 80 nm or less), the reflectance in the range of 400 nm or more and 700 nm or less can be increased, and the refractive index of the resin layer (X) can be decreased. If the thickness of the resin layer (X) is increased, the minimum reflectance can be lowered. The minimum reflectance in the range of 400 nm or more and 700 nm or less is more preferably 5.5% or more and 6.3% or less.

  In the laminated film of the present invention, the resin layer (X) preferably has a polycyclic aromatic hydrocarbon structure. The polycyclic aromatic hydrocarbon structure is a hydrocarbon composed of two or more aromatic rings (condensed rings) exhibiting aromaticity, and a typical structure is a naphthalene structure. The polycyclic aromatic hydrocarbon structure of the present invention includes heteroaromatic compounds in which a part of carbon is substituted with nitrogen. Since the resin layer (X) has a polycyclic aromatic hydrocarbon structure, not only can the UV resistance of the resin layer (X) be improved, but also can suppress a decrease in adhesion due to UV irradiation in the processing step. When the refractive index of the resin (α) is increased, the luminance of the prism sheet can be improved when used as an easily adhesive film for a prism sheet. In addition, although it is preferable that a polycyclic aromatic hydrocarbon structure is contained in resin ((alpha)) mentioned later, it is not this limitation.

  Since the resin layer (X) of the laminated film of the present invention has a specific range of surface energy changes before and after UV irradiation treatment, which will be described later, good general-purpose adhesion to UV-curable solventless paints such as prism resins. Expresses sex. Therefore, when the laminated film of the present invention is applied to a prism sheet substrate and used as a prism sheet, it can be reflected in the luminance without impairing the refractive index of the resin (α), and the luminance is improved. If the change in surface energy before and after the UV irradiation treatment described later is outside a specific range, the resin layer (X) becomes insufficient in adhesion, and between this laminated film and a UV curable solventless paint such as a prism resin. In addition, a fine air layer (air bubbles) due to poor adhesion is generated, and incident light cannot be reflected efficiently and accurately, and is partially scattered, resulting in a decrease in luminance. By maintaining not only the initial adhesiveness but also the adhesiveness due to UV irradiation and the adhesiveness in a moist heat environment, it is possible to suppress a decrease in luminance after each treatment.

  In the laminated film of the present invention, at least one surface layer is preferably a resin layer (X).

(2) Isocyanate compound (A)
Examples of the isocyanate compound (A) that can be used in the present invention include tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, metaxylylene diisocyanate, hexamethylene-1,6-diisocyanate, 1,6-diisocyanate hexane, Tolylene diisocyanate and hexanetriol adduct, tolylene diisocyanate and trimethylolpropane adduct, polyol-modified diphenylmethane-4,4′-diisocyanate, carbodiimide-modified diphenylmethane-4,4′-diisocyanate, isophorone diisocyanate, 1,5- Naphthalene diisocyanate, 3,3′-bitrylene-4,4 ′ diisocyanate, 3,3′dimethyldiphenylmethane-4,4′-diisocyanate, metaphenylene diisocyanate Anate can be used. In particular, when a polymer type isocyanate compound having a plurality of isocyanate groups is used at the terminal or side chain of a polymer such as polyester resin or acrylic resin, the flexibility and toughness of the resin layer can be obtained when a laminated film is formed. Therefore, it can be preferably used.

  Furthermore, since the isocyanate group easily reacts with water, a blocked isocyanate compound in which the isocyanate group is masked with a blocking agent or the like can be suitably used from the viewpoint of pot life of the coating agent. A typical example of the blocking agent is a system in which the blocking agent is volatilized by heating after coating and heat in the drying process, and an isocyanate group is exposed to cause a crosslinking reaction. The isocyanate group may be either a monofunctional type or a polyfunctional type, but a polyfunctional type block polyisocyanate compound can be suitably used from the viewpoint that the crosslink density is easily increased. A branched blocked isocyanate is preferable. The presence of a plurality of branched isocyanate groups at the ends and side chains of polymers such as polyester resins and acrylic resins improves the crosslink density of the resin layer (X) compared to linear blocked isocyanate, and UV Resistant resin layer (X) can be created. The isocyanate compound (A) preferably has a polycyclic aromatic hydrocarbon structure. Since the isocyanate compound (A) has a polycyclic aromatic hydrocarbon structure, not only can the UV resistance of the resin layer (X) be improved, but also can suppress a decrease in adhesiveness due to UV irradiation in the processing step, When used as an easily adhesive film for a prism sheet, the brightness of the prism sheet can be improved by increasing the refractive index of the resin (α). Examples of the low molecular or high molecular compound having two or more blocked isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, trimethylol propane tolylene diisocyanate 3 mol adduct, polyvinyl isocyanate, vinyl isocyanate copolymer, polyurethane. Uses terminal diisocyanate, tolylene diisocyanate methyl ethyl ketone oxime block, hexamethylene diisocyanate sodium hyposulfite block, polyurethane terminal diisocyanate methyl ethyl ketone oxime block, phenol block to trimethylol propane tolylene diisocyanate 3 mol adduct be able to.

(3) Resin (α)
It is preferable that resin ((alpha)) of this invention contains what heated the resin composition containing an isocyanate compound (A). Moreover, it is preferable that the structure content derived from an isocyanate compound (A) in a resin ((alpha)) is 50 to 95 mass%. When the content of the structure derived from the isocyanate compound (A) is 50% by mass or more, good adhesiveness of the resin layer (X) can be expressed. On the other hand, when the content of the structure derived from the isocyanate compound (A) is 95% by mass or less, the change in the surface energy (the sum of polar force, hydrogen bonding force, and dispersion force) before and after UV irradiation treatment is 15 mN / m. It is possible to:
In addition, various binder resins such as polyester resin, urethane resin and acrylic resin, various additives such as lubricants, inorganic particles, organic particles, surfactants, antioxidants, thermal initiators, etc., characteristics of the resin layer (X) You may add to such an extent that it does not worsen.
In particular, when used as an easy-adhesion film for a prism sheet, the brightness of the prism sheet is improved by increasing the refractive index of the resin (α). Therefore, various binder resins such as polyester resin, urethane resin, and acrylic resin have a refractive index. It preferably has an improved polycyclic aromatic hydrocarbon structure.

(4) At least one compound (B) selected from melamine compounds, oxazoline compounds, and carbodiimide compounds
In the present invention, the resin (α) forming the resin layer may contain at least one compound (B) selected from a melamine compound, an oxazoline compound, and a carbodiimide compound in addition to the isocyanate compound (A). The mass of the compound (B) is preferably 5% by mass or more and 30% by mass or less when the resin (α) forming the resin layer (X) is 100% by mass.

  The melamine compound (B) that can be used in the present invention needs to have at least one triazine ring and one methylol group in one molecule. By using this melamine compound (B), the resin (α) can have a cross-linked structure between methylol groups.

  Specifically, the melamine compound is preferably a compound obtained by condensing a methylol melamine derivative obtained by condensing melamine and formaldehyde and dehydrating and condensing methyl alcohol, ethyl alcohol, isopropyl alcohol or the like as a lower alcohol.

  Examples of methylolated melamine derivatives include monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, and hexamethylol melamine.

  The oxazoline compound is not particularly limited as long as it has at least one oxazoline group or oxazine group per molecule, but an addition polymerizable oxazoline group-containing monomer is preferable, and 2-vinyl-2-oxazoline, 2-vinyl- 4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl -2-oxazoline.

The carbodiimide compound is not particularly limited as long as it has at least one carbodiimide structure represented by the following formula (1) per molecule. Polycarbodiimide compounds having at least one are particularly preferred. In particular, when a polymer type isocyanate compound having a plurality of carbodiimide groups is used at the terminal or side chain of a polymer such as polyester resin or acrylic resin, the resin layer of the present invention is provided on the polyester film, In this case, not only the hardness of the resin layer is improved and the oligomer precipitation is suppressed, but also adhesion to various inks and hard coat agents, wet heat and heat resistance, flexibility, and toughness can be preferably used.
-N = C = N- Formula (1)
A known technique can be applied to the production of the carbodiimide compound, and it is generally obtained by polycondensation of a diisocyanate compound in the presence of a catalyst. As the diisocyanate compound which is a starting material of the polycarbodiimide compound, aromatic, aliphatic, alicyclic diisocyanate and the like can be used. Specifically, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate. , Isophorone diisocyanate, dicyclohexyl diisocyanate and the like can be used. Furthermore, in order to improve the water solubility and water dispersibility of the polycarbodiimide compound within the range not losing the effect of the present invention, a surfactant is added, polyalkylene oxide, quaternary ammonium salt of dialkylamino alcohol, hydroxy A hydrophilic monomer such as an alkyl sulfonate may be added or used.

  Other compounds such as aziridine compounds, amide epoxy compounds, titanate coupling agents such as titanium chelates, methylolated or alkylolated urea compounds, acrylamide compounds, and the like can be optionally used.

(5) Polyester film The laminated film of the present invention is a laminated film having a resin layer (X) on at least one surface of the polyester film. Polyester is a general term for polymers having an ester bond as a main bond chain, and includes ethylene terephthalate, propylene terephthalate, ethylene-2,6-naphthalate, butylene terephthalate, propylene-2,6-naphthalate, ethylene. Those having at least one component selected from -α, β-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate as a main component can be preferably used. In the present invention, it is preferable to use polyethylene terephthalate as the polyester film. When heat or shrinkage stress acts on the thermoplastic resin film, it is preferable to use polyethylene-2,6-naphthalate having excellent heat resistance and rigidity.

  The polyester film is preferably biaxially oriented. A biaxially oriented polyester film is generally an unstretched polyester sheet or film that is stretched about 2.5 to 5 times in the longitudinal direction and in the width direction perpendicular to the longitudinal direction, and then subjected to heat treatment to produce crystals. The alignment is completed, and it indicates a biaxial alignment pattern by wide-angle X-ray diffraction. When the polyester film is not biaxially oriented, the thermal stability of the laminated film, particularly the dimensional stability and mechanical strength are insufficient, or the flatness is poor.

  In the polyester film, various additives such as antioxidants, heat stabilizers, weathering stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents. An agent, a nucleating agent, etc. may be added to such an extent that the properties are not deteriorated.

  The thickness of the polyester film is not particularly limited and is appropriately selected depending on the application and type, but is preferably preferably 10 to 500 μm, more preferably 20 to 250 μm from the viewpoint of mechanical strength, handling properties, and the like. Most preferably, the thickness is 30 to 150 μm. The polyester film may be a composite film obtained by coextrusion or a film obtained by bonding the obtained film by various methods.

  The laminated film of the present invention preferably has a total light transmittance of 88% or more. When the total light transmittance of the laminated film is 88% or more, it can be suitably used as an optical film such as an easily adhesive film for prisms. Since the upper limit of the substantial total light transmittance of the polyester film is 94%, it is preferably 88% or more and less than 94%.

  The laminated film of the present invention preferably has a haze of 0.3% or more and less than 3.0%. By setting the haze of the laminated film in the above range, it can be suitably used for optical films that require transparency.

(6) Formation method of resin layer (X) The method of forming resin layer (X) of this invention apply | coats the resin composition containing an isocyanate compound (A) to at least one surface of a polyester film, heats, It is obtained by a step of forming a resin layer (X) containing the resin (α). In this formation method, in addition to the isocyanate compound (A), the resin (α) includes various binder resins such as polyester resins, urethane resins, and acrylic resins, cross-linking agents such as melamine compounds and carbodiimide compounds, cross-linking catalysts for isocyanate compounds, Various additives such as a lubricant, inorganic particles, organic particles, a surfactant, an antioxidant, and a thermal initiator may be included.

  Moreover, when apply | coating the resin composition containing an isocyanate compound (A) on a polyester film, the solvent (D) may be contained in the resin composition. That is, the resin (α) containing the isocyanate compound (A) may be dissolved or dispersed in the solvent (D) to obtain a resin composition, which may be applied to a polyester film. After the application, the solvent is dried and heated to obtain a film on which the resin layer (X) is laminated.

  Here, the aqueous solvent (D) is water or water and alcohols such as methanol, ethanol, isopropyl alcohol and butanol, ketones such as acetone and methyl ethyl ketone, and glycols such as ethylene glycol, diethylene glycol and propylene glycol. The organic solvent that is soluble is mixed at an arbitrary ratio. In the present invention, it is preferable to use an aqueous solvent (D) as a solvent. This is because by using an aqueous solvent, rapid evaporation of the solvent in the heating step can be suppressed, and not only a uniform resin layer can be formed, but also the environmental load is excellent.

  As a method for applying the resin composition to the polyester film, either an in-line coating method or an off-coating method can be used, but an in-line coating method is preferable. The in-line coating method is a method of applying in the process of manufacturing a polyester film. Specifically, it refers to a method of coating at any stage from melt extrusion of a polyester resin to biaxial stretching followed by heat treatment and winding up, and is generally substantially non-obtainable after melt extrusion and rapid cooling. Crystalline unstretched (unoriented) polyester film (A film), then uniaxially stretched (uniaxially oriented) polyester film (B film) stretched in the longitudinal direction, or biaxially before heat treatment stretched further in the width direction It is applied to any one of stretched (biaxially oriented) polyester film (C film).

  In the present invention, the resin composition is applied to any one of the A film and B film of the polyester film before crystal orientation is completed, the solvent is evaporated, and then the polyester film is uniaxially or biaxially. It is preferable to employ a method in which the resin film is provided while being stretched and heated to complete the crystal orientation of the polyester film. According to this method, the polyester film can be formed, the resin composition can be applied, the solvent can be dried, and the heating (that is, the resin layer can be formed) at the same time. Moreover, it is easy to make the thickness of the resin layer thinner in order to perform stretching after coating.

  Especially, the method of apply | coating a resin composition to the film (B film) uniaxially stretched to the longitudinal direction, drying a solvent, and extending | stretching to the width direction after that, and heating is excellent. After applying to an unstretched film, compared to the method of biaxial stretching, the stretching process is less than once, so it is difficult for defects and cracks of the resin layer due to stretching to occur, and a resin layer excellent in transparency and smoothness can be formed. Because.

  On the other hand, the off-line coating method is different from the film-forming process on the film after the A film is stretched uniaxially or biaxially and subjected to heat treatment to complete the crystal orientation of the polyester film, or the A film. This is a method of applying a resin composition in the process. In this invention, it is preferable to provide by the in-line coating method from the various advantages mentioned above.

  Therefore, the best method for forming the resin layer (X) in the present invention is to apply a resin composition using an aqueous solvent (D) onto a polyester film using an in-line coating method, and dry the aqueous solvent (D). And forming by heating.

(7) Adjustment method of resin composition When preparing a resin composition, it is preferable to use an aqueous solvent (D) as a solvent. The resin composition is prepared by mixing and stirring the isocyanate compound (A), which is water-dispersed or water-solubilized as necessary, the other binder resin, and the aqueous solvent (D) in a desired weight ratio. Can do. Subsequently, various additives such as a lubricant, inorganic particles, organic particles, a surfactant, an antioxidant, and a thermal initiator are added in any order as necessary so as not to deteriorate the characteristics of the resin layer provided by the resin composition. Can be mixed and stirred. The mixing and stirring methods can be performed by shaking the container by hand, using a magnetic stirrer or stirring blade, irradiating ultrasonic waves, vibrating and dispersing.

(8) Coating method As a coating method of the resin composition on the polyester film, a known coating method such as a bar coating method, a reverse coating method, a gravure coating method, a die coating method, or a blade coating method may be used. it can.

(9) Method for producing laminated film The laminated film of the present invention is a production having a step of forming a resin layer (X) by applying a resin composition containing an isocyanate compound (A) to at least one surface of a thermoplastic resin film. Is the method.

Hereinafter, the method for producing a laminated film of the present invention will be described in detail by taking, as an example, a case where a polyethylene terephthalate (hereinafter abbreviated as PET) film is used as a polyester film. It is not a thing.
First, PET pellets are sufficiently vacuum-dried, then supplied to an extruder, melt extruded into a sheet at about 280 ° C., and cooled and solidified to produce an unstretched (unoriented) PET film (A film). This film is stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially oriented PET film (B film). A resin composition prepared to a predetermined concentration is applied to one side of the B film. At this time, surface treatment such as corona discharge treatment may be performed on the coated surface of the PET film before coating. By performing surface treatment such as corona discharge treatment, the wettability of the resin composition to the PET film can be improved, the repelling of the resin composition can be prevented, and a uniform coating thickness can be achieved.

  After coating, the edge of the PET film is held with a clip and guided to a heat treatment zone (preheating zone) of 80 to 130 ° C., and the solvent of the coating solution is dried. After drying, the film is stretched 1.1 to 5.0 times in the width direction. Subsequently, it is guided to a heating zone (heat treatment zone) at 150 to 250 ° C. and subjected to heat treatment for 1 to 30 seconds to complete crystal orientation and complete formation of the resin layer. In this heating step (heat treatment step), 3 to 15% relaxation treatment may be performed in the width direction or the longitudinal direction as necessary. The thus obtained laminated film has a change in surface energy (the sum of polar force, hydrogen bonding force and dispersion force) before and after UV irradiation treatment of the resin layer (X) of 0.1 mN / m or more and 15 mN / m or less. It is transparent, and is excellent in general-purpose adhesiveness with respect to a solvent-free paint such as a prism resin.

(Characteristic measurement method and effect evaluation method)
The characteristic measuring method and the effect evaluating method in the present invention are as follows.

(1) Measurement of total light transmittance and haze Three points (three) of square-shaped laminated film samples each having a side of 5 cm are prepared. The sample is then allowed to stand for 40 hours in a normal state (23 ° C., relative humidity 50%). Each sample was measured with a turbidimeter “NDH5000” manufactured by Nippon Denshoku Industries Co., Ltd., and the total light transmittance was measured according to JIS “Testing method of total light transmittance of plastic transparent material” (K7361-1, 1997 edition). ), Haze is measured by a method according to JIS “How to Obtain Haze of Transparent Materials” (K7136, 2000 edition). The total light transmittance and haze value of each of the three points (three) are averaged to obtain the total light transmittance and haze value of the laminated film.

(2) Calculation method of dispersion force, polarity force, and hydrogen bonding force First, the laminated film was allowed to stand for 24 hours in an atmosphere of room temperature 23 ° C. and relative humidity 65%. Thereafter, the contact angle of each of the four types of solutions of pure water, ethylene glycol, formamide, and diiodomethane with respect to the resin layer under the same atmosphere was measured using a contact angle meter CA-D (Kyowa Interface Science Co., Ltd.). ) To measure 5 points each. The average value of the three measured values excluding the maximum value and the minimum value of the five measured values is defined as the contact angle of each solution.

Next, using the contact angles of the four types of solutions obtained, “the surface free energy (γ) of the solid, which is proposed by Hata et al., Is expressed as a dispersion force component (γ _S ^d ) and a polar force component (γ _S ^p ). , And the hydrogen bonding force component (γ _S ^h ), and the geometric mean method based on the expanded Fowkes equation (expanded Fowkes equation) ”, the dispersion force, polar force, hydrogen bonding force and The surface energy that is the sum of the dispersion force and the polar force is calculated.

A specific calculation method is shown. The meaning of each symbol is described below. When γ _S ^L is the tension at the interface between the solid and the liquid, Equation (1) is established.

γ _S ^L : surface energy of the resin layer and known solutions listed in Table 1 γ _S : surface energy of the resin layer γ _L : surface energy of known solutions listed in Table 1 γ _S ^d : surface energy of the resin layer Dispersion force component γ _S ^p : Polar force component of the surface energy of the resin layer γ _S ^h : Hydrogen bond force component of the surface energy of the resin layer γ _L ^d : Dispersion force component of the surface energy of the known solution described in Table 1 γ _L ^p : Polar force component of surface energy of known solutions listed in Table 1 γ _L ^h : Hydrogen bond strength component of surface energy of known solutions listed in Table 1 γ _S ^L = γ _S + γ _L −2 (γ _S ^d · γ _L ^d ) ^1/2 -2 (γ _S ^p · γ _L p) ^1/2 -2 (γ _S ^h · γ _L ^h ) ^1/2 (1).

  The state when the smooth solid surface and the droplet are in contact with each other at the contact angle (θ) is expressed by the following equation (Young's equation).

γ _S = γ _S ^L + γ _L cos θ (2)

When these mathematical formulas (1) and (2) are combined, the following formula is obtained.
_{^{(γ S d · γ L d}} ) 1/2 + (γ S p · γ L p) 1/2 + (γ S h · γ L h) 1/2 = γ L (1 + cosθ) / 2 ··· formula (3).

Actually, the four components of water, ethylene glycol, formamide, and diiodomethane have contact angles (θ) and the components of the surface tension of known solutions listed in Table 1 (γ _L ^d , γ _L ^p , γ _L ^h ) is substituted into Equation (3) to solve the four simultaneous equations. As a result, the surface energy (γ), the dispersion force component (γ _S ^d ), the polar force component (γ _S ^p ), and the hydrogen bonding force component (γ _S ^h ) of the solid are calculated. The dispersion force of the present invention corresponds to the dispersion force component (γ _S ^d ), and the polarity force of the present invention corresponds to the sum of the polar force component (γ _S ^p ) and the hydrogen bonding force component (γ _S ^h ).

(3) Measurement of reflectance The laminated film cut into A4 cut size was divided into 3 parts each in length and width, and a total of 9 points were used as measurement samples. The long side was defined as the longitudinal direction. Spectral reflectance is measured by using a 50 mm wide black glossy tape (Yamato Co., Ltd., vinyl tape No. 200-50-21: black) on the back surface of the measurement surface (the resin layer) so as not to bite bubbles. After the sample and the tape were aligned in the longitudinal direction, the sample was cut into about 4 cm square sample pieces, and the spectrophotometer (UV2450 manufactured by Shimadzu Corporation) was measured at an incident angle of 5 ° (the resin layer). The spectral reflectance of was measured.
The direction in which the sample was set in the measuring instrument was adjusted to match the longitudinal direction of the sample in the front-rear direction toward the front of the measuring instrument. In order to standardize the reflectance, an attached Al ₂ O ₃ plate was used as a standard reflecting plate. As a measurement range of the reflectance, a range in which a wavelength of 400 nm to 700 nm can be measured was selected. The measurement was performed on nine measurement samples, and the average value of the nine points was determined as the reflectance.

(4) Initial adhesion evaluation A solventless UV curable resin was prepared as follows.

-Sanyo Chemical Co., Ltd. "Sun Rad" RC-610: 60 parts by weight Mitsubishi Rayon Co., Ltd. "Diabeam" UR-6530: 20 parts by weight Nippon Kayaku Co., Ltd. DPHA: 20 parts by weight.
Solventless UV curable resin, applied to the composition layer surface of the laminated film so as to have a thickness of about 10 μm by the wire bar coating method, and then using an ultraviolet lamp with an irradiation intensity of 120 W / cm, The ink surface distance was 12 cm, the conveyor speed was 2 m / min, and the UV intensity was applied at an integrated intensity of about 300 mJ / cm ² to be cured. Adhesion evaluation was performed by the below-mentioned crosscut method.

<Cross cut method>
According to JIS5600-5-6 (established in 1999), 5 × 5 25 squares are cut into the obtained UV curable resin evaluation sample according to JIS 5600-5-6 (established in 1999). Next, Nichiban 18 mm cello tape (registered trademark) (product number: CT-18S) is rubbed into the cut part, and the cello tape (registered trademark) is rubbed firmly with fingers so that the cut is visible. Then, the cellophane (registered trademark) is instantaneously peeled off at an angle of about 60 ° with respect to the resin layer. Count the number of strips. The number of evaluations is five, and the average value is obtained. Evaluation criteria are defined as follows. Evaluation criteria “A” and “B” are determined as good adhesion.

A: The number of cells peeled is 1 cell or less. B: The number of cells peeled exceeds 1 cell and 3 cells or less. C: The number of cells peeled exceeds 3 cells.

(5) Adhesion evaluation after UV irradiation The sample for UV curing resin evaluation obtained in the previous item (4) Initial adhesion evaluation was set at a height of 12 cm from the surface of the surface to be UV cured, and the irradiation intensity was 120 W / cm. A condensing type high-pressure mercury lamp (H03-L31, manufactured by Eye Graphics Co., Ltd.) is irradiated with ultraviolet rays so that the integrated irradiation intensity is 500 mJ / cm ² or more and 1000 mJ / cm ² or less, and is cured. Thereafter, adhesion is evaluated by the cross-cut method described in (3).

(6) Structure confirmation of resin layer (X) The confirmation method of whether the resin layer (X) has a urethane bond, an acryloyl group, or a polycyclic aromatic hydrocarbon structure is not particularly limited to a specific technique, but Such a method can be illustrated. For example, the presence or absence of a weight peak derived from each structure is confirmed by gas chromatography mass spectrometry (GC-MS). Next, the presence or absence of a peak derived from a bond between atoms of each structure is confirmed by Fourier transform infrared spectroscopy (FT-IR). Furthermore, proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) confirms the position of the chemical shift derived from the position of the hydrogen atom in each structure and the proton absorption line area derived from the number of hydrogen atoms. A method of comprehensively confirming these results is preferable.

(7) Luminance measurement evaluation after prism sheet molding A prism sheet sample was prepared as follows. (4) The solventless UV curable resin composition adjusted in the initial adhesive evaluation was applied to a mold such as a mold or a resin mold corresponding to the prism pattern, and the solventless UV curable resin composition After smoothing the surface, the laminated film was formed by superimposing the composition layer surface on the solventless UV curable resin composition side and curing it by UV irradiation. The UV irradiation conditions were an ultraviolet lamp with an irradiation intensity of 120 W / cm, an irradiation distance (distance between the lamp and the ink surface) of 12 cm, a conveyor speed of 2 m / min, and an integrated intensity of about 300 mJ / cm ² .
Using a liquid crystal display device using a sidelight-type backlight having a surface brightness of 7000 cd / m ² , the obtained prism sheet sample is placed on the backlight, and the surface on which the prism is provided is opposed to the liquid crystal display portion. The luminance (cd / m ² ) is measured using CS-200 manufactured by Konica Minolta Sensing Co., Ltd., and the relative luminance (%) is obtained by the following formula.
Relative luminance (%) = (measured value when a sample is placed) / (measured value of light source only) × 100
Evaluation criteria are defined as follows. Evaluation criteria “A” and “B” are determined as good luminance.

A: Relative luminance is 92.5% or more B: Relative luminance is 90% or more and less than 92.5% C: Relative luminance is less than 90%.

Example 1
The resin composition was adjusted as follows.
-Branched isocyanate compound (A):
“Elastotron” (registered trademark) E-37 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

-At least one compound (B) selected from melamine compounds, oxazoline compounds, and carbodiimide compounds:
Oxazoline-containing polymer aqueous dispersion (“Epocross” (registered trademark) WS-500, manufactured by Nippon Shokubai Co., Ltd.), carbodiimide aqueous crosslinking agent (Nisshinbo Chemical Co., Ltd. “Carbodilite” (registered trademark) V-04), melamine resin water A mixture of 20 parts / 20 parts / 30 parts of sol (“WATERSOL” (registered trademark) S-695 manufactured by DIC Corporation).

  In order to impart lubricity to the resin layer surface to the aqueous solution containing at least one compound (B) selected from the obtained blocked isocyanate compound (A), melamine compound, oxazoline compound, and carbodiimide compound, inorganic particles 2 parts by mass of silica particles having a number average particle diameter of 170 nm (“Snowtex” (registered trademark) MP-2040, manufactured by Nissan Chemical Industries, Ltd.) were added to 100% by mass of the resin composition. Furthermore, in order to improve the applicability on the polyester film, a fluorosurfactant (Plus Coat (registered trademark) RY-2 manufactured by Kyoyo Chemical Co., Ltd.) is added to the resin composition and water (D). It added so that it might become 0.03 mass part with respect to a total of 100 mass parts.

・ Laminated film:
PET pellets (extreme viscosity 0.63 dl / g) substantially free of particles are sufficiently vacuum dried, then supplied to an extruder, melted at 285 ° C., extruded into a sheet form from a T-shaped die, and electrostatically applied Using a casting method, it was wound around a mirror casting drum having a surface temperature of 25 ° C. to be cooled and solidified. This unstretched film was heated to 90 ° C. and stretched 3.3 times in the longitudinal direction to obtain a uniaxially stretched film (B film).

  Next, an aqueous solution containing the resin composition was applied to a uniaxially stretched film with a coating thickness of about 6 μm using a bar coat. Subsequently, both ends in the width direction of the uniaxially stretched film coated with the resin composition (II) were held by clips and led to the preheating zone. The atmospheric temperature of the preheating zone was set to 90 ° C. to 100 ° C., and the solvent contained in the aqueous solution containing the resin (α) was dried. Subsequently, the film was continuously stretched 3.5 times in the width direction in a stretching zone at 100 ° C., and then heat treated for 20 seconds in a heat treatment zone at 235 ° C. to form a resin layer (X). A completed laminated film was obtained. In the obtained laminated film, the thickness of the PET film is 100 μm, the thickness of the resin layer (X) is 50 nm, the resin layer (X) has a urethane bond, and has a polycyclic aromatic hydrocarbon structure. There wasn't.

  The characteristics of the obtained laminated film are shown in the table. Both initial adhesiveness and adhesiveness after UV irradiation were good for solventless resins.

(Examples 2 to 5)
A laminated film was obtained in the same manner as in Example 1 except that the isocyanate compound (A) and the compound (B) were changed to mass ratios described in the table. In the obtained laminated film, the thickness of the PET film is 100 μm, the thickness of the resin layer (X) is 50 nm, the resin layer (X) has a urethane bond, and has a polycyclic aromatic hydrocarbon structure. There wasn't.
The characteristics of the obtained laminated film are shown in the table. Both initial adhesiveness and adhesiveness after UV irradiation were good for solventless resins.

(Example 6)
A laminated film was obtained in the same manner as in Example 3 except that the compound (B) was changed to the following and the coating thickness was changed. In the obtained laminated film, the thickness of the PET film is 100 μm, the thickness of the resin layer (X) is 70 nm, the resin layer (X) has a urethane bond, and has a polycyclic aromatic hydrocarbon structure. There wasn't.
The characteristics of the obtained laminated film are shown in the table. Both initial adhesiveness and adhesiveness after UV irradiation were good for solventless resins.

-At least one compound (B) selected from melamine compounds, oxazoline compounds, and carbodiimide compounds:
20 parts each of an oxazoline-containing polymer aqueous dispersion (“Epocross” (registered trademark) WS-500 manufactured by Nippon Shokubai Co., Ltd.) and melamine resin water sol (“WATERSOL” (registered trademark) S-695 manufactured by DIC Corporation) / 30 parts mixed.

(Example 7)
A laminated film was obtained in the same manner as in Example 3 except that the isocyanate compound (A) was changed to the following and the coating thickness was changed. In the obtained laminated film, the thickness of the PET film was 100 μm, the thickness of the resin layer (X) was 40 nm, and the resin layer (X) had a urethane bond and a polycyclic aromatic hydrocarbon structure.
The characteristics of the obtained laminated film are shown in the table. Both initial adhesiveness and adhesiveness after UV irradiation were good for solventless resins.
-Linear isocyanate compound (A):
At a reactor internal temperature of 55 ° C., 100 parts of hexamethylene diisocyanate (manufactured by Tosoh Corp.) and 80 parts of methyl ethyl ketoxime were added to perform a blocking reaction to obtain a blocked isocyanate compound. The blocked isocyanate compound was emulsified with an aqueous caustic soda solution (3.5 parts of NaOH dissolved in 500 parts of water), and then the methyl ethyl ketone solvent was distilled off under reduced pressure to obtain a linear isocyanate compound (A).

(Example 8)
A laminated film was obtained in the same manner as in Example 3 except that the isocyanate compound (A) was changed to the following. In the obtained laminated film, the PET film had a thickness of 100 μm, the resin layer (X) had a thickness of 50 nm, and the resin layer (X) had a urethane bond and a polycyclic aromatic hydrocarbon structure.
The characteristics of the obtained laminated film are shown in the table. Both initial adhesiveness and adhesiveness after UV irradiation were good for solventless resins.
-Branched isocyanate compound (A):
In a methyl ethyl ketone solvent, to 100 parts of polypropylene glycol (average molecular weight 1100), 98 parts of polymeric MDI (polymethylene polyphenyl polyisocyanate, average molecular weight 360) and 12.2 parts of dimethylolpropionic acid were added, and the temperature inside the reactor system was increased. Reaction was performed under 75 degreeC and the isocyanate compound was obtained. Next, 32 parts of methyl ethyl ketoxime was added at a system temperature of 55 ° C., and a blocking reaction was performed to obtain a blocked isocyanate compound. The blocked isocyanate compound was emulsified with an aqueous caustic soda solution (3.5 parts of NaOH dissolved in 550 parts of water), and then the methyl ethyl ketone solvent was distilled off under reduced pressure to obtain a branched isocyanate compound (A).

Example 9
The same method as in Example 8 except that the following polyester resin was added and the mass ratio of the resin composition was branched isocyanate compound (A) / compound (B) / polyester resin (C) = 60/25/15. Thus, a laminated film was obtained. In the obtained laminated film, the PET film had a thickness of 100 μm, the resin layer (X) had a thickness of 50 nm, and the resin layer (X) had a urethane bond and a polycyclic aromatic hydrocarbon structure.
The characteristics of the obtained laminated film are shown in the table. Both initial adhesiveness and adhesiveness after UV irradiation were good for solventless resins.
-Polyester resin The water dispersion of the polyester resin which consists of the following copolymer composition was adjusted.
<Copolymerization component>
(Dicarboxylic acid component)
Dimethyl 2,6-naphthalenedicarboxylate: 88 mol%
5-Dimethylsodium sulfosulfophthalate: 12 mol%
(Diol component)
Compound in which 2 mol of ethylene oxide is added to 1 mol of bisphenol S: 86 mol%
1,3-propanediol: 14 mol%
(Comparative Examples 1 and 2)
A laminated film was obtained in the same manner as in Example 1 except that the isocyanate compound (A) and the compound (B) were changed to mass ratios described in the table. In the obtained laminated film, the thickness of the PET film is 100 μm, the thickness of the resin layer (X) is 50 nm, the resin layer (X) has a urethane bond, and has a polycyclic aromatic hydrocarbon structure. It wasn't. The characteristics of the obtained laminated film are shown in the table. The initial adhesiveness was good with respect to the solventless resin, but the adhesiveness after UV irradiation was reduced.
(Comparative Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the isocyanate compound (A) and the compound (B) were changed to mass ratios described in the table. In the obtained laminated film, the thickness of the PET film was 100 μm, the thickness of the resin layer (X) was 50 nm, and the resin layer (X) did not have a urethane bond and a polycyclic aromatic hydrocarbon structure. The characteristics of the obtained laminated film are shown in the table. Not only the initial adhesiveness but also the adhesiveness after UV irradiation was poor for solventless resins.

  The present invention has a resin layer that has general-purpose adhesiveness, particularly for solvent-free paints such as prism resins, and also maintains good adhesiveness by suppressing a decrease in adhesiveness due to UV irradiation in the processing step. The present invention relates to a laminated film. When a prism sheet is formed on the laminated film, it has excellent luminance, and therefore can be used for optical films for displays and touch panels, particularly prism sheets.

Claims (11)

A laminated film having a resin layer (X) on at least one surface of a polyester film, wherein the resin layer (X) has surface energy before and after UV irradiation treatment under the following conditions (polarity force, hydrogen bonding force and dispersion force). The change in the sum (surface energy after UV irradiation treatment-surface energy before UV irradiation treatment) is from 0.1 mN / m to 15 mN / m.
[UV irradiation conditions]
UV irradiation device: Condensing type high-pressure mercury lamp (H03-L31, manufactured by Eye Graphics Co., Ltd.)
Irradiation intensity: 120 W / cm
Irradiation distance (distance between UV irradiation device and irradiated object): 12cm
Integrated irradiation intensity: 500 mJ / cm ² or more and 1000 mJ / cm ² or less. The resin layer (X) has a change in the sum of the polar force and the hydrogen bonding force before and after the UV irradiation treatment under the above conditions (the sum of the polar force after the UV irradiation treatment and the hydrogen bonding force-the polar force before the UV irradiation treatment) The laminated film according to claim 1, wherein the sum of hydrogen bonding forces is 10 mN / m or less. The laminated film according to claim 1 or 2, wherein the resin layer (X) has a urethane bond and / or an acryloyl group. The laminated film according to any one of claims 1 to 3, wherein the minimum reflectance in a wavelength range of 400 nm to 700 nm measured from the resin layer (X) side is 5.0% to 6.5%. The laminated film according to any one of claims 1 to 4, wherein the resin layer (X) has a polycyclic aromatic hydrocarbon structure. The laminated film according to any one of claims 1 to 5, which is used as an easily adhesive film for a prism sheet. A method for producing a laminated film satisfying the following (1) and (2) having a resin layer (X) on at least one surface of a polyester film,
The manufacturing method of a laminated | multilayer film including the process of apply | coating the resin composition containing an isocyanate compound (A) to at least one surface of a polyester film, and forming the resin layer (X) which consists of resin ((alpha)) obtained by heating.
(1) Change in surface energy (sum of polar force, hydrogen bonding force and dispersion force) before and after UV irradiation treatment under the following conditions (surface energy after UV irradiation treatment-before UV irradiation treatment) Surface energy) of 0.1 mN / m or more and 15 mN / m or less.
(2) The resin layer (X) has a change in the sum of the polar force and the hydrogen bonding force before and after the UV irradiation treatment under the following conditions (the sum of the polar force and the hydrogen bonding force after the UV irradiation treatment-before the UV irradiation treatment). The sum of the polar force and the hydrogen bond strength) is less than 10 mN / m.
[UV irradiation conditions]
UV irradiation device: Condensing type high-pressure mercury lamp (H03-L31, manufactured by Eye Graphics Co., Ltd.)
Irradiation intensity: 120 W / cm
Irradiation distance (distance between UV irradiation device and irradiated object): 12cm
Integrated irradiation intensity: 500 mJ / cm ² or more and 1000 mJ / cm ² or less. The method for producing a laminated film according to claim 7, wherein the isocyanate compound (A) is a branched block isocyanate. The method for producing a laminated film according to claim 7 or 8, wherein the isocyanate compound (A) has a polycyclic aromatic hydrocarbon structure. The method for producing a laminated film according to any one of claims 7 to 9, wherein the content of the isocyanate compound (A) in the resin composition is 50 to 95 mass%. The manufacturing method of the laminated | multilayer film in any one of Claims 7-10 in which the said resin composition contains the at least 1 sort (s) of compound (B) chosen from a melamine compound, an oxazoline compound, and a carbodiimide compound.